1. Field of the Invention
The present invention relates to an electroacoustic transducer for transducing sound and an acoustic transducing system employing such an acoustic transducer.
2. Description of the Prior Art
Acoustic transducers and acoustic transducing systems such as a headphone apparatus, an earphone apparatus, and so on have been proposed in which an acoustic signal (i.e., an audio signal) is supplied in the form of an electrical signal and the acoustic signal is transduced into a sound to thereby reproduce the sound.
Such an acoustic transducer is generally comprised of an acoustic transducing unit (i.e., a speaker unit) for transducing an acoustic signal to a sound. The acoustic transducer formed as a headphone apparatus is constructed such that a pair of acoustic transducer units are supported on a listener's two auricles in an opposing fashion.
An acoustic transducing system is generally comprised of a pair of left and right speakers used as an acoustic transducer for transducing an acoustic signal into a sound. Each of these speakers is comprised of a speaker unit serving as an acoustic transducing unit having a diaphragm and a speaker cabinet for housing the speaker unit such that the sound emanating surface thereof is opposed to the outside. In this acoustic transducing system, the speakers apparatus are disposed so as to oppose the listener from the front and the sound is reproduced by the speakers.
In the acoustic transducer constructed as the headphone apparatus as described above, since the acoustic transducing units constructing the acoustic transducer are opposed to the eardrums of the listener, a standing wave occurs between the acoustic transducing units and the eardrums. Because of the occurrence of the standing wave, the listener using such acoustic transducer feels pressure and a so-called lateralization.
Further, in the above acoustic transducer, since the the acoustic transducing units are supported so as to substantially close the external auditory meatus of the listener, it becomes difficult for the listener wearing this acoustic transducer to hear sound from the outside. As a consequence, when walking or driving a car while wearing this acoustic transducer, the listener cannot hear what is going on around the listener so that the listener cannot walk and drive a car safely.
In the above acoustic transducing system, in order to reproduce sound satisfactorily in a wide frequency band including a low frequency band, the speaker cabinet constructing the speaker units must be increased in volume and the diaphragms of the speaker units also must be increased in area. If the volume of the speaker cabinet and the area of the diaphragm are increased, then the acoustic transducer system is unavoidably enlarged in size.
Even in the acoustic transducing system in which the system is enlarged in size in order to satisfactorily reproduce sound in a wide frequency band, if an annoyance to the neighbors and the like are taken into consideration because of dwelling circumstances, and so forth, it is then frequently observed that sound cannot be reproduced with sufficient sound pressure.